Annealing apparatus and method



SePt- 9, 1941. c. B. HOAK 2,255,617

ANNEALING APPARATUS AND METHOD Filed July 20, 1940 2 Sheets-Sheet l sept 9, 1941. c. B. HoAK l 2,255,617

ANNEALING APPARATUS AND METHOD Filed July 20, 1940 2 Sheets-Sheet 2 f IQ. E.

Patented Sept. 9, 1941 ANNEALING APPARATUS AND METHOD Clarence B. Hoak, Steubenville, Ohio Application July 2o, 1940, serial No. 346,559

14 Claims.

My invention relates to annealing furnaces and a method of annealing, and constitutes in part a continuation of my application Serial No. 156,382, led July 29, 1937 (Patent No. 2,219,363) and in part an improvement upon the disclosure of the said application.

One object of my invention is to provide an l improved method of heating material within an annealing furnace, both by radiation and convection.

Another object of my invention is to provide a means and a method whereby material may be heated more uniformly and the application of heat to various portions of the material be more efficiently and effectively controlled than by various means and methods heretofore 'employed.

Another object of my invention is to provide a portable annealing furnace of such form that no particular arrangement of base or foundation is required therefor.

Still another object of my invention is to provide a portable annealing furnace which has means formed integrally therewith for circulating heating gases in the furnace.

A further object of my invention is to provide a portable annealing furnace having exhaust passageways for the gases, formed integrally therewith. 'l In the accompanying drawings, Figure 1 is a. perspective view of a portion lof a furnace embodying my invention; Fig. 9 is a cross sectional view through a complete furnace, taken on the line II--II of Fig. 3; and Fig. 3 is a horizontal sectional View taken on the line III-III of Fig. 2.

While the furnace is here shown as of rectangular form, it will beunderstood that my invention is applicable also to furnaces of horizontally-circular form.

As mentioned above, the furnace is of the portable type. and can be placed on any flat foundation or anywhere on a mill floor, such as that indicated at 4, thus rendering it unnecessary to', provide a base of special form or one which has passageways for the. exhaust of gases.

9 that in turn support refractory lining or bricks I0, a suitable arch roof Il being also provided.

Vertically-extending combustion chambers I2, that serve as heat-radiating tubes, are disposed along each side of the furnace, and aresecured against the side Walls of the furnace by .retaining bars I 5 that are held in place by tie bolts I3, which extend through the walls of the furnace and are in turn supported by the outer surfaces of the beams 5, through the medium of yieldable plates or washers I4 which are interposed between the heads of the bolts and the adjacent surfaces of the beams.v These combustion chambers or radiating tubes may conveniently be made in two parts, as shown, and can be formed of a metal alloy which will withstand annealing temperatures, or may be of clay or other suitable refractory material.

Burnery pipes or nozzles I6 extend through the side walls of the furnace into the combustion chambers I2, their inner ends being upturned so that the ame will not be impinged directly against the vertical walls of the combustion chambers. The burners may be of any suitable type, for the combustion gas, fuel oil or powdered. fuel. Fuel for the burners is supplied through fuel lines Il from a suitable source of supply, the lines being disconnectable from said source of supply to permit removal of the furnace after the completion of an annealing operation. The supply offuel to each burner I6 is controlled by a valve I8, so that the burners can be regulated individually to control the degree 'to which the furnace chamber is heated at various points throughout its length. A burner lighting and inspection aperture is provided at I5a foi` each v of the burners I6.

Conduits I9 extend through the furnace walls, in a plane below the plane of the burners, and lead from the interior of the lfurnace chamber to headers 20 that are disposed exteriorly of the furnace and are carried fby the framework thereof. At each sigle of the furnace a verticallyextending conduitl leads from the header 20.

and through a fan or fan casing 2,2 to an upper header 23. the headers 23 and the furnace chamber by conduits 24. The fan or blower at22 is'vdriven by a suitable motor (not shown), in such direction that the heating gases /are drawn from the lower portion of the chamberv and discharged into the chamber through the conduits 24. This circulation of the gases makes for faster heating of the material within the furnace, since heat will be absorbed more rapidly from a moving Communication is aiilorded between gases can be had to the atmosphere or toa stack v (not shown) in case it is desiredto vent `all or v some of the heating gases at some stage of operation.

From the foregoing, it will be seen that the annealing furnace and apparatus constitute a self-contained unit which can be readily placedy over or `removed from annealing boxes 30 andy V3| that are mounted uponbases 32 and33 respectively, which are inrturn supported upon bricks or pillars 34 and 35 respectively, that arespaced apart to permit circulation of heating gases beneath the annealing boxes.

Another important feature of my invention resides in the fact that a portion of the gases will be drawn downwardly between each row of radiant tubes and the adjacent side of an annealing box, as indicated by the arrows 3B and 31, while another and larger portion of the gases will be drawn downwardly between the annealing boxes, as indicated by the arrows V38. These latter flows of lgases pass beneath the annealing boxes and are drawn into the conduits I9 along with those gases flowing downwardly along the paths 36 and 31. The gases flowing downwardly at 36 and 31 exert an opposing and spreading effect upon theheat rays from the radiant tubes I2, lthereby effecting diffusion of such rays and avoiding hot spots on the sides of the annealing boxes. This diffusion or spreading of the radiated heat is useful also where a continuous radiating wall instead of a series of radiating tubes or combustion chambers is employed, as shown for example in my said patent, particularly when a series of burners is provided throughout lthe length of the heating chamber.

Also, it will be apparent that a fan-produced draft is not necessary in order to attain this object, since natural or stack draft may ber employed, as in my said patent, and also in the present case if the valves 21 are closed and the4 valves26 and 28 opened. f'

ausser? '2. The method which comprises heetinr a chamber by radiation from heated elements that are laterally spaced along each side of the chamber, and simultaneously creating a cw of heated gases along the radiating surface of each element that is exposed within the chamber, ina direction parallel to the plane of said surface along paths each substantially equal in width to the width of the adjacent radiating surface.

3. The method of heating a chamber that contains a plurality of work bodies, which comprises supplying radiated heat to said bodies from vertically defined zones adjacent to thesides of the chamber, and causing a vertical Aflow of heated gases, in paths each of approximately the widthA heat radiating tubes within theA chamberl and each having one side exposed to the lwork-receivk ing space, means forheating the `interior of the It will be understood ythat the fan22fn1aybez-'fr'r driven in the reverse directionV so asy to cause,

withdrawal of the gases from the upper portion of the furnace and inflow 'thereof to the lower portion of the furnace. It will also be understood that'the upper conduits can lead through the roof of the furnace instead of through the side walls. l

With particular reference to the method claimed herein, of causing a flow of gases along a radiating surface such as the tubes I2 or a continuous radiating wall, it will be understood that said process contemplates also movement of the gases upwardly or horizontally along radiating surfaces.

I claim as my invention: i 1. The method which comprises heating a chamber by radiation froml heated elements that are laterally spaced along each side of the chamber, and simultaneously creating a downow of "heated gases along the radiating surface of 4each element Ithat is exposed within the chamber along paths each substantially equal in width to the width of the adjacent radiating surface.

tubes, and means for directing a flow of gases in a controlled path along that surface of each tube which is exposed to the work.

5. Annealing apparatus comprising a chamber, heat radiating tubes within the chamber and eachhaving one side exposed to the work-receiving space, means for heating the interior of the tubes, and means for directing a downow of gases from out of the upper end of each tube and in a controlled path -along that surface thereof Y,

sageway and along-its foremost exposed surface, Y

toward the other end of said surface, in a path ybetween the Work-receiving area and the said surface.

7. Annealing apparatus comprising a chamber, passageways located adjacent to the inner walls of the chamber and arranged in laterally-spaced relation, the'passageways each being open to the chamber-.at one-end, means for introducingheatvving gases into rthe otherendslof the passageways,

the 'passagewaysv havingj'front walls exposed-to the interior area of the chamber and serving as heat-radiating elements, and means for. effecting flow of gases from the open end of each passageway and along its foremost exposed surface, toward the other end of said surface, in a path between the work-receiving area and the said surface, each flow path being confined mainly to a singleA passageway surface.

8. Annealing apparatus comprising a chamber, laterally-spaced heat-radiant tubes adjacent to the inner Walls of the chamber and having front Walls exposed to the interior area of the chamber, the tubes being openvto the chamber at one end, means for introducing heating gases into the other ends of the tubes. and means forr effecting flow of gases from the open endlof each tube and along its foremost exposed, surface, toward the other end ofsaid surface, in a pathv 4between the tube and the work-receiving area.

'9. Annealing apparatus comprising a chamber, passageways located adjacent to the inner walls of the chamber and arranged in laterally-spaced relation, the passageways each being open to the chamber at the upper end, means for introducing heating gases into the lower ends of the passageways, the passageways having front walls exposed to the interior area of the chamber and serving as heat-radiating elements, and means for effecting fiow of gases from the open end of each passageway and along its foremost exposed surface, toward the other end of said surface, in a path between the work-receiving area and the said surface.

10. Annealing apparatus comprising a. chamber, passageways located adjacent to the inner vlalls'of the chamber and arranged in laterallyspaced relation, the passageways each being open to the chamber at one end, means for introducing heating'gases into the other ends of the passageways, the passageways having front walls exposed to the interior area of the chamber and serving as heat-radiating elements, means for effecting fiow of gases from the open end of each passageway and along its foremost exposed surfece, toward the other end of said surface, in a path between the work-receiving area and the` said surface, and means for'returning the said' flows of gases to points adjacent tothe open ends of the passageways.

11. Annealing apparatus comprising a cham- V ber, passageways located adjacent to the inner walls of the chamber and arranged in laterallyspaced relation, the passageways each being open to the chamber at the upper end, means for introducing heating gases into the lower ends of the passageways, the passageways having front walls exposed to the interior area of the chamber and serving as heat-radiating elements, means for effecting flow of gases from the open end of each passageway and along its foremost exposed surface, toward the other end of vsaid surface, in a path between the work-receiving area and the said surface, and means for withdrawing the said flows of gases from the furnace, at points adjacent to the lower ends of the passageways and returning them into the upper portion of the chamber.

`12. Annealing apparatus comprising furnace walls forming an annealing chamber, verticallyextending and laterally-spaced combustion chambers of generally rectangular form in cross section mounted within the annealing chamber, in proximity to the inner faces of the furnace side walls, and each open at one end for the discharge of heating gases into the annealing chamber, and burners discharging directly into the otherends of the combustion chambers, the combustion chamber walls being of a character and form to radiate a substantial portion of the heat.

13. Annealingapparatus comprising furnace walls forming an annealing chamber, verticallyextending and laterally-spaced combustion chambers of generally'rectangular form in cross section mounted within the annealing chamber, in proximity to-the inner faces of the furnace side walls and each open at its upper end for the discharge of heating gases into the annealing L chamber,l and burners discharging directly into the lower ends of the combustion chambers, the combustion chamber walls being of a character and form to radiate a substantial portion ofv the heat.

1.4. Annealing apparatus comprising furnace walls forming an annealing chamber, verticallyextending and laterally-spaced passageways for combustion-gases, formed within the annealing chamber, in proximity to the inner faces of the furnace walls and each open at one end for the discharge of heating gases into the annealing chamber, and burnersv discharging directly into the other ends of the passageways, the innermost walls of the passageways being of a character and form to radiate a substantial portion of the heat, and the lateral spacing of the pas- Asageways not substantially greater than the width of the wall surfaces at the innermost sides of the passageways.

CLARENCE B. HOAK. 

